What Can We Learn about GRB from the Variability Timescale Related Correlations?

Xie, Wei; Lei, Wei‐Hua; Wang, Ding-Xiong

doi:10.3847/1538-4357/aa6718

Cited by 16 publications

(20 citation statements)

References 49 publications

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“…As shown in Xie et al (2017), this model can hardly reproduce the observed MT S − L correlation. It is worth mentioning that they defined MT S as the viscous timescale due to the viscous instability.…”

Section: Discussionmentioning

confidence: 87%

An MAD explanation for the correlation between bulk Lorentz factor and minimum variability time-scale

Lloyd-Ronning

Lei

Xie

2018

Monthly Notices of the Royal Astronomical Society

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We offer an explanation for the correlation between the minimum variability timescale (MT S) in the prompt emission light curve of gamma-ray bursts (GRBs) and the estimated bulk Lorentz factor of these GRBs, in the context of a magnetically arrested disk (MAD) model. In particular, we show that previously derived limits on the maximum available energy per baryon in a Blandford-Znajek jet leads to a relationship between the characteristic MAD timescale, t M AD , in GRBs and the maximum bulk Lorentz factor: t M AD ∝ Γ −6 , somewhat steeper than (although within the error bars of) the fitted relationship found in the GRB data. Similarly, the MAD model also naturally accounts for the observed anti-correlation between MT S and gamma-ray luminosity L in the GRB data, and we estimate the accretion rates of the GRB disk (given these luminosities) in the context of this model. Both of these correlations (MT S − Γ and MT S − L) are also observed in the AGN data, and we discuss the implications of our results in the context of both GRB and blazar systems.

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Section: Discussionmentioning

confidence: 87%

An MAD explanation for the correlation between bulk Lorentz factor and minimum variability time-scale

Lloyd-Ronning

Lei

Xie

2018

Monthly Notices of the Royal Astronomical Society

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“…Yi et al (2017b) compared the observational results with a positive correlation between Γ0 (the initial Lorentz factor) and the jet power from the two types of BH central engine models, i.e.,the ν ν -annihilation mechanism (non-magnetized model) and the Blandford & Znajek mechanism (hereafter BZ, a strongly magnetized model), and they found that some parameters are contrived for the ν ν -annihilation mechanism, whereas the latter (BZ) mechanism can generally account for the observations, which also can be seen in Lei et al (2013). The result is further confirmed by Xie et al (2017), and by using the empirical correlation between Lorentz factor and minimum variability timescale. If X-ray fares are indeed powered by the BZ mechanism of a hyper-accreting BH system, then what can we learn about the properties of GRB central engine from these X-ray flares data?…”

Section: Introductionmentioning

confidence: 75%

“…As discussed in Lei et al (2013), Xie et al (2017) and Yi et al (2017b), two parameters of prompt emission, i.e., the beaming corrected γ-ray luminosity Lγ and initial Lorentz factor Γ0, are highly related to the properties of GRB central engines, and thus used to study the properties of central objects. X-ray flares are believed to be generated by the late activities of central engine.…”

Section: Sample Selectionmentioning

confidence: 99%

Constraining Properties of GRB Central Engines with X-ray flares

Yi,

Xie,

et al. 2021

Preprint

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X-ray flares in gamma-ray bursts (GRBs) are believed to be generated by the late activities of central engine, and thus provide an useful tool to diagnose the properties of central objects. In this paper, we work on a GRB X-ray flare sample whose bulk Lorentz factors are constrained by two different methods and the jet opening angles are determined by the jet breaks in afterglow lightcurves. Considering a hyperaccreting stellar-mass black hole (BH) as the central engine of GRBs and the Blandford & Znajek process (BZ) as the jet production mechanism, we constrain the parameters of central engine by using the X-ray flare data. We find that the BZ mechanism is so powerful making it possible to interpret both GRB prompt emissions and bright X-ray flares. The wind parameter (p) and accreted mass (M d ) fall into reasonable ranges. Our result is also applied to GRB 170817A. The late X-ray flare in GRB 170817A, if it is true, might not be a BH origin.

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“…The hyper-accreting BH system can launch a relativistic jet via neutrino-antineutrino annihilation (Popham et al 1999;Narayan et al 2001;Di Matteo et al 2002;Gu et al 2006;Chen & Beloborodov 2007;Janiuk et al 2004Janiuk et al , 2007Liu et al 2007Liu et al , 2015Lei et al 2009Lei et al , 2017Xie et al 2016), or Blandford-Znajek mechanism (hereafter BZ; (Blandford & Znajek 1977;Lee et al 2000;Li 2000;Lei et al 2005Lei et al , 2013). The neutrino annihilation mechanism suffers strong baryon loading from the disk and therefore may be too "dirty" to account for a GRB jet Xie et al 2017). For this reason, we suppose that the jet powering the X-ray bump is dominated by the BZ mechanism.…”

Section: The Modelmentioning

confidence: 99%

Signature of a Newborn Black Hole from the Collapse of a Supra-massive Millisecond Magnetar

Chen

Xie

Lei

et al. 2017

ApJ

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The X-ray plateau followed by a steep decay ("internal plateau") has been observed in both long and short gamma-ray burst (GRBs), implying a millisecond magnetar operating in some GRBs. The sharp decay at the end of plateau, marking the abrupt cessation of the magnetar central engine, has been considered as the collapse of a supra-massive magnetar to a black hole (BH) when it spins down. If "internal plateau" is indeed the evidence of a magnetar central engine, a natural expectation is a signature from the new-born BH in some candidates. In this work, we find that GRB 070110 is a particular case, which shows a small X-ray bump following its "internal plateau". We interpret the plateau with a spin-down supra-massive magnetar and the X-ray bump with a fall-back BH accretion. This indicates that the new-born BH is likely active in some GRBs. Therefore, GRB 070110-like events may provide a further support to the magnetar central engine model and enable us to investigate the properties of the magnetar as well as the new-born BH.

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What Can We Learn about GRB from the Variability Timescale Related Correlations?

Cited by 16 publications

References 49 publications

An MAD explanation for the correlation between bulk Lorentz factor and minimum variability time-scale

An MAD explanation for the correlation between bulk Lorentz factor and minimum variability time-scale

Constraining Properties of GRB Central Engines with X-ray flares

Signature of a Newborn Black Hole from the Collapse of a Supra-massive Millisecond Magnetar

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